Operating mechanism for a circuit interrupter

ABSTRACT

A dual-acting piston operable within an operating cylinder is mechanically connected to the moving contact structure of a circuit breaker. The piston has a portion constantly acted upon in the closing direction by a high-pressure operating fluid. A large portion of the piston structure is at low pressure, and the opposite face of the piston structure is alternately pressurized or exhausted to effect, respectively, an opening or a closing operation of the circuit breaker. A portion of the piston structure fits into a recess thereby affording a shock-absorbing function during the closing operation. Another portion of the piston structure traps highpressure operating fluid so as to constitute a shock absorber during the opening operation of the interrupter. In the case that a gas is used, which tends to liquefy, provision is made for the removal of the liquefied gas during the operation of the mechanism.

0 United States Patent 1151 3,639,713

Fischer et al. Feb. 1, 1972 [54] OPERATING MECHANISM FOR A 3,005,07710/1961 Forwald ..200/l48 CIRCUIT INTERRUPTER 3,094,601 6/1963 Forwald.200/148 B 3,264,440 8 1966 Forwald ..200 148 [72] Inventors: William H.Fischer, Pittsburgh; Wayne S. I I

Aspey, Monroev1llc, both of Pa. Primary RI Sec V [73] Assignee:Westinghouse Electric Corporation, Pitt- Attorney-A. T. Stratton, C. L'McHale and W. R. Crout sburgh, Pa. [22] Filed: Dec. 10, I968 [57]ABSTRACT A dual-acting piston operable within an operating cylinder is IAppl' mechanically connected to the moving contact structure of acircuit breaker. The piston has a portion constantly acted [521 11.8. CI..200/ 148 R, ZOO/82A upon in the closing direction by a high-pressureoperating l 5 1 Int. Cl. ..H0lh 35/38 fluid. A large portion of thepiston structure is at low pressure, l Field Search I484, and theopposite face of the piston structure is alternately 9 l 399 pressurizedor exhausted to effect, respectively, an opening or a closing operationof the circuit breaker. [56] References Cited A portlon of the pistonstructure fits into a recess thereby af- UNlTED STATES PATENTS fording ashock-absorbing function during the closing opera- 1,051,510 1/1913Nazel et al ..92/10 the T; g g 'f 2,740,859 4/1956 Beatty et al. .200/82B opelatmg so *2: 2 me as DC a Sm er unng 3,205,787 9/1965 Volkmann.......91/399 M Pemng 3,302,533 l 7 "utter et L- In the case that a gas isused, which tends to liquefy, provision 3,407,709 10/1968 Bade....9l/399 X is made for the removal of the liquefied gas during theopera- 2,435,162 1/1948 Scott, Jr ..200/148 x on fth mechanism.2,555,898 6/1951 Paterson et al. .....200/148 X 2,783,338 2/ 1957 Beatty..200/82.l X 13 Claims, 16 Drawing Figures LOW PRESSURE SP GAS 5 F g i4.53 H 54 8 8b X I j 56 1% E 80 NORMALLY 10 1 CLOSED 4& s H

"02; a-as gr Q S'\\- H|GH PRESSURE 67 SFG GAS T0 16 1X enssgun is' i- I690 :III 3 slml, 7

mimmm um 1639.713 SHEEI OIBF 12 WITNESSES INVE NTORS William H, Fischerand woyneS. Aspey ATTORNEY SHEEI 03 0F 12 PATENIEB FEB lmz ma ma PNETEUFEB 7 E 2 SHEET UMJF12 PATENTEDFEB H972 I 34639.71 3

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OPERATING MECHANISM FOR A CIRCUIT INTERRUPTER CROSS-REFERENCE TO RELATEDAPPLICATIONS In US Pat. application filed Sept. 25, 1969 Ser. No.762,479, now US. Pat. No. 3,590,189, issued June 29, I971 to William H.Fischer and Wayne S. Aspey there is described a pneumatic pistonstructure for operating the movable contacts of a circuit interrupterincluding an opening piston and a closing piston, both fixedly securedto, and movabe with the piston rod operating the contacts. In thisapplication, a separate shock absorber was utilized to eliminate shockduring the opening and closing operations of the interrupter.

BACKGROUND OF THE INVENTION It is desirable, in providing a circuitbreaker, particularly of the high-voltage and high-rating type, toprovide an operating mechanism, which is reliable and efficient bringingabout, at desired times, a quick-opening and a quick-closing operationof the contact structure. In addition, as well known by those skilled inthe art, it is desirable to provide means for cushioning the movableparts near the ends of their opening and closing strokes. On the otherhand, the provision for the shock-absorbing function must not interferewith a rapid opening and closing movement of the piston structureitself, which during a major portion of such opening and closingstrokes, must move unhindered by the action of shock-absorbing elements.

Also, it is desirable to provide a mechanism of relatively few parts andtaking up little space. Finally, it is desirable to associate positivelywith the moving contact structure an indicator indicating, with positiveassurance, the open and closed circuit positions of thecircuitinterrupter contacts. This is highly essential to prevent dangerto operating personnel during maintenance.

SUMMARY OF THE INVENTION In accordance with a preferred embodiment ofthe invention, there is provided a dual-acting piston structurepositively tied to the movable contacts of a circuit breaker, which, bya suitable configuration thereof, not only provides a structure which isbiased to the closed circuit position, but, additionally, has portionsperforming shock-absorbing functions during the opening and closingoperations of the interrupter. In the instant invention, a pistonstructure has a stepped portion, which moves within a high-pressurechamber and operates to bias the contact structure to the closedposition, and also serves as a shock absorber during the openingoperation of the interrupter. Preferably, another portion of the pistonstructure moves within a recess during'the closing operation, trappingtherein additional gas to serve as a shock absorber during the closingstroke of the interrupter.

Further objects and advantages will readily become apparent upon readingthe following specification, taken in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an end elevational view of athree-phase circuit breaker embodying the principles of the presentinvention;

FIG. 2 is a side elevational view of the three-phase circuit breaker ofFIG. I;

FIG. 3 is a top plan view of the circuit breaker of FIGS. 1 and 2;

FIG. 4 diagrammatically indicates the interconnecting linkage betweenthe ground potential operator and the valve control rods for the severalinterrupting assemblies;

FIGS. 5A, 5B and 5C collectively illustrate a cross-sectional view takenthrough the circuit breaker of FIGS. 1-3 illustrating the contactstructure in the closed circuit position;

FIG. 6 is a vertical sectional view taken through the highpotentialoperator illustrating the improved operating mechanism of the presentinvention, the contact structure being illustrated in the closed circuitposition;

FIG. 6A is a diagrammatic view of the differential piston areas of thepiston of FIG. 6;

FIG. 7 is a vertical sectional view of a portion of the contactstructure for the circuit breaker, the contacts being illustrated in thefully open circuit position;

FIG. 8 is a view somewhat similar to that of FIG. 7, but illustratingthe contact structure in the closed circuit position thereof;

FIG. 9 is a plan view, in section, taken substantially along the lineIX-IX of FIG. 6; 1

FIG. I0 is a vertical sectional view taken through the lower portion ofthe circuit breaker structure indicating the extension of the valvecontrol rods;

FIG. 11 is a detailed view taken in the direction of the arrows of FIG.10;

FIG. I2 illustrates a modified form of the invention, the pistonstructure being illustrated in the closed circuit position of theinterrupter; and,

FIG. 13 is a view similar to that of FIG. 12, but illustrating theposition of the piston structure of FIG. 12 in the fully open circuitposition.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawings, andmore particularly to FIGS. 1-3 thereof, the reference numeral 1generally designates a three-phase circuit breaker. As shown in FIGS.I-3, it will be apparent that the circuit breaker structure 1 issupported by a metallic framework 2, which may be composed of heavyangle iron braces 3 and struts-4. The circuit breaker structure I isgenerally of the dual-pressure type involving the use of a suitablearc-extinguishing gas 5 at two different pressures, namely a highpressure say 230 p.s.i. suitable for use for injecting into the are 6(FIG. 7) to effect the extinction thereof, and, additionally, being usedin the operating mechanism 7 (FIG. 6) to effect actuation of the pistonstructure 8 associated therewith.

Generally, as shown in FIGS. 2 and 3, the several pole units, A, B, andC are spaced laterally apart upon the grounded supporting framework 2,and are mechanically interconnected to a common mechanism 10 at groundpotential, diagrammatically indicated in FIG. 4 of the drawings.

Briefly, the manner of operation of the circuitbreaker structure I issuch as to cause the actuation of the ground potential operator 10 toeffect motion of a mechanical linkage II, which interconnects theseveral three-way valve control rods 13 extending upwardly individuallywithin the three arc-extinguishing assemblages 15, more clearly shown inFIGS. 2 and 3 of the drawings. As illustrated diagrammatically in FIG.5A of the drawings, the valve control rod'13, moving only a shortdistance, extends upwardly within insulating supporting tubes I7disposed interiorly of an insulating inner tension tube 18 serving tospacially relate theme or more pairs of contact structures 20, which maybe employed. As shown in FIG. 5A, only a single pair of separablecontact structures 20 is utilized; however, for the higher voltages andhigher ratings, a plurality of pairs of contact structures 20 may beutilized, if desired.

Generally, the arc-extinguishing assemblage 15 comprises an outerinsulating weatherproof insulating casing 22, which maybe formed eitherof porcelain, or of a suitable resinous material serving to enclose thearc-extinguishing structure 24 of the interrupter l. Thearc-extinguishing structure, or assemblage 15 is supported upon thegrounded housing 26 and is slanted, or canted away from aterminal-bushing structure 28, which serves to cause the current path tobe conducted in a generally U-shape as shown in FIG. I. Thetenninal-bushing structure 28 generally has a terminal rod 29 at highvoltage extending therethrough, and is spaced within an outerweatherproof casing 30, composed of a suitable insulating material, suchas porcelain, as shown in FIG. 5C. A suitable arc-extinguishing gas,which has high insulating qualities, may be enclosed within theterminal-bushing structure 28 at a relatively low pressure, say of 60p.s.i. This gas may be the same gas 5 as described heretofore.

FIGS. 5A, 5B; 5C collectively show a vertical cross-sectional view takenthrough a single pole unit A of the threephase circuit interrupter 1. Aswell known by those skilled in the art, there are three such structuresA, B and C to control the three phases of a transmission system.

In the circuit breaker structure I under consideration a suitable highlyeffective arc-extinguishing gas 5, such as sulfur hexafluoride (SP gas,may be used as the arc-extinguishing gas, and also as an insulating gasto enable a close spacing of the live parts. It is also used as theinsulating gas within the terminal-bushing structure28. U.S. Pat. No.2,757,261 describes the arc-extinguishing characteristics of thisparticular gas 5.

As mentioned hereinbefore, generally, the manner of operation is thesimultaneous actuation of the three valve control rods 13, which extendupwardly into the tops of the arc-extinguishing assemblages 15. Here, asis shown more clearly in FIG. 6 of the drawings, the upper ends of thevalve control rods 13 are biased upwardly by a battery of compressionsprings 31 seating upon a movable spring seat 32 affixed to the valvecontrol rod 13, as at 34, and serving to bias the pressurebalancedthree-way control valve 36 to its upper closed position. To effect anopening operation of the circuit breaker 1, the valve control rod 13 ismoved upwardly say three-quarters of an inch, so as to permit theadmission of high-pressure gas 5, existing within the region 37,upwardly through a conduit 39 and across the entire lower surface 8C ofa dual-acting piston structure 8, which is connected, by means of apiston rod 41, to the movable contact structure 20 of the interrupter 1.

As shown more clearly in FIG. 6, taken in conjunction with FIG. 7, itwill be observed that the piston structure 8 is mechanically tied, bymeans of the piston rod 41, to a generally ladder-shaped structure 43,which comprises a pair of laterally spaced insulating operating rods 44,which extend axially of the arc-extinguishing assemblages through a pairof hollow supporting tubes 45.

The region 47, immediately adjacent the contact structure 20, andexternally thereof in the closed circuit position thereof, asillustrated in FIG. 8, is at a relatively high pressure, say 230 p.s.i.,as more clearly described in the U.S. Pat. application filed'Sept. 16,I968, Ser. No. 759,992 by Berkabile, the arc-extinguishing structure 24being of the so-called downstream type, in which the high-pressure gas 5moves into and through the separated contact structure during theopening operation until the flow of gas is halted by the closingoperation of a pair of downstream blast valves indicated by thereference numerals 49 and 50in FIG. 8 of the drawings.

With reference to FIGS. 6 and 6A of the drawings, it will be observedthat the dual-acting piston 8 has a differential annular area 8x equalto the difference of area of 8a-8d, herein termed the effective closingarea portion of the piston 8):. This effective closing area 8 isconstantly subjected to a high-pressure gas within the region 51. Inaddition, the piston structure 8 has the upper closing face portion 8bthereof constantly subjected to gas at a relatively low pressure, whichtends to effect closing operation of the piston 8, and hence the movablecontact structure 20. The annular area, which is effective in openingthe mechanism is 8c-8x. The area that is effective in closing is 8a-8dor 8x. The area, which is effective for the opening shock absorber is8a. The area that is effective for the close shock absorber is 8d asshown in FIG. 6A.

To effect an opening operation of the interrupter 1, actuation of thethree-way valve 36 is brought about by upward movement of the valvecontrol rod 13 to admit gas upon the entire lower face 80 of the pistonstructure 8 causing opening upward motion of the contact structure 20,and, additionally, trapping high-pressure gas within the space 51 andcausing its slow leakage through the ports 53 provided in the annularcheck valve 54. During the closing operation, upon downward movement .ofthe piston structure 8, the check valve 54 raises and permitshigh-pressure gas, which is constantly present within the region 56 toflow past the ring-shaped check valve 54 and into the region 51.

During the closing operation, the downward movement of the pistonstructure 8 effects the downward movement of a stepped portion 8dthereof into the space 58, which contains gas at relatively highpressure at all times. This performs a shock-absorbing function duringthe closing stroke, the gas leaking through perforations 59 provided ina ring-shaped check valve 60. v

F ixedly attached to the piston structure 8 and in effect constitutingan extension of the piston rod 41 is an indicator stem 62, which carriesa green flag 63, which projects upwardly into a transparent cap 64provided at the upper end of the interrupter, as shown in FIG. 6. Thisclearly indicates to maintenance people, in a positive manner, the factthat the circuit breaker has its contact structure in the fully opencircuit position, and that it is then safe to work upon the breaker, ifdesired. This structure is set forth and'claimed in U.S. Pat.application (W.E.40,6l2) filed Dec. 31, I969, Ser. No. 889,635, byRichard E. Kane and Wm. H. Fischer and assigned to the assignee of theinstant application.

The three-way valve structure 36 comprises movable valve seats 66, 67,which take care of any misalignment or elongation or contraction of thevalve control rods 13, which may be of considerable length. Inaddition,the valve seats 66, 67 are spring biased in a direction to effectfollowing travel, once the lips 36a, 36b of the valve have separatedtherefrom.

To take care of the situation where a low ambient temperature may beencountered, and liquefaction of the sulfur-hexafluoride gas isencountered, liquid pipes may be provided, as indicated by the referencenumerals 69 and 70..

The liquefaction pipe 70 communicates with the space below the pistonstructure 8, which may be at alternately low and high pressure. Theliquefaction pipe 69 communicates with the space 37 which is constantlyat high pressure. Preferably, ball check valves 71, 72 areprovided toprevent the leakage of high-pressure gas admitted from the high-pressurereservoir leaking into the space 39 during low-pressure conditionstherein. When the pressure is equalized at the ball valves, the liquidwill flow downwardly bygravity down the pipes 69a, 70 and eventuallyleads into the high-pressure reservoir 24 within the arc-extinguishingchamber, and also within the lower U-bend, where suitably providedheaters may be located to vaporize the liquefied gas.

FIGS. 12 and 13 illustrate a modified form of the invention in which thepiston structure 73 has a stepped portion 73a, which moves within aspace 75 constantly at high pressure. Again it will be observed that thering-shaped check valve 76 is provided to bring about a shock-absorbingfunction during the opening operation of the interrupter. Additionally,a space 77 is provided below a stepped portion 73b of the pistonstructure 73 to provide a shock-absorbing action during the closingoperation. High-pressure gas is constantly fed into the region, 78.Relatively low-pressure gas exists in the space 80 above the pistonstructure 73. Generally, the operation of the piston structure 73 ofFIGS. 12 and I3 is similarly to that previously described in connectionwith the piston structure of FIG. 6 of the drawings.

From the foregoing description, it will be apparent that there has beenprovided an improved operating mechanism 7 for a circuit breaker inwhich, by a suitable configuration of the piston structure, 8, 73 ashock-absorbing function is built in to cushion the opening and closingstrokes of the interrupter. There results a simplification of parts andhighly reliable operation is achieved by the resulting simplicity. Inaddition, means has been provided for accommodating liquefaction of thearc-extinguishing gas during relatively low ambient operatingconditions.

Although there has been illustrated and described specific structures,it is to be clearly understood that the same were merely for the purposeof illustration, and that changes and modifications may readily be madetherein by those skilled in the art without departing from the spiritand scope of themvention.

We claim as our invention:

l. A gas-operating mechanism for a circuit interrupter including, incombination:

a. a piston rod adaptable for connection to the separable contactstructure of the circuit interrupter;

b. a dual-acting stepped piston structure secured to said piston rod andhaving a first stepped portion (8a) movable within a shock-absorbingchamber (51) constantly filled with high-pressure operating fluidpartially tending to bias said piston structure to the closed circuitposition at all times;

c. said piston having one side thereof (8b) constituting the majorclosing face portion thereof acted upon by lowpressure operating fluidat all times tending to close the contact structure, and,

d. means for alternating the pressure upon the opposite opening face(8c) of the piston structure for producing opening and closingoperations of the circuit interrupter.

2. The combination according to claim 1, wherein the dualacting pistonstructure is generally cup-shaped and has an outer annular flangeportion constituting said first portion (8a) of the piston structuremovable within said shock-absorbing chamber.

3. The combination according to claim I, wherein a portion (8d) of thepiston structure moves within a second shock-absorbing chamber (58)constantly filled with high-pressure operating fluid at all times andtending to bias the piston structure to the open position.

4. The combination of claim 1, wherein an indicator rod is affixed tothe piston structure and is visible externally of the circuitinterrupter so as to be visible to maintenance personnel.

5. The combination of claim 1, wherein a three-way control valvecontrols the admission or exhausting of high-pressure fluid on theopening face of the piston structure.

6. The combination of claim 1, wherein a liquefaction duct connects tothe shock-absorbing chamber (51 7. In combination, a pneumatic operatingmechanism for a circuit interrupter including a cup-shaped steppedoperating piston having an enlarged piston head flange portion (8a) atone end movable within an enlarged high-pressure shock-absorbing chamber(51) at all times, said piston having low-pressure fluid constantlyacting on a portion (8b) of the closing face thereof, and means foralternating the highand low-pressure fluid acting on the oppositeenlarged piston head flange portion (8:) to effect the opening andclosing operations of the circuit interrupter.

8. The combination according to claim 7, wherein the cupshaped operatingpiston 8d) has an enlarged guide portion at the other end thereof ofsmaller diameter than the diameter of said enlarged piston head flangeportion (8a), and a radially inwardly extending operating cylinderportion bearing against the smallest diameter of the piston.

9. The combination according to claim 1, wherein the head of the pistonhas a reduced protruding portion extending into a shock-absorbingchamber to cushion the closing stroke of the interrupter.

10. The combination of claim 9, wherein a check valve is associated withthe last-mentioned shock-absorbing chamber.

11. The combination according to claim 1, wherein a check valve isassociated with said shock-absorbing chamber.

12. The combination according to claim 3, wherein a check valve isassociated with the second shock-absorbing chamber.

13. The combination according to claim 12, wherein a check valve isassociated with the first-mentioned shock-absorbing chamber.

1. A gas-operating mechanism for a circuit interrupter including, incombination: a. a piston rod adaptable for connection to the separablecontact structure of the circuit interrupter; b. a dual-acting steppedpiston structure secured to said piston rod and having a first steppedportion (8a) movable within a shock-absorbing chamber (51) constantlyfilled with highpressure operating fluid partially tending to bias saidpiston structure to the closed circuit position at all times; c. saidpiston having one side thereof (8b) constituting the major closing faceportion thereof acted upon by low-pressure operating fluid at all timestending to close the contact structure, and, d. means for alternatingthe pressure upon the opposite opening face (8c) of the piston structurefor producing opening and closing operations of the circuit interrupter.2. The combination according to claim 1, wherein the dual-acting pistonstructure is generally cup-shaped and has an outer annular flangeportion constituting said first portion (8a) of the piston structuremovable within said shock-absorbing chamber.
 3. The combinationaccording to claim 1, wherein a portion (8d) of the piston structuremoves within a second shock-absorbing chamber (58) constantly filledwith high-pressure operating fluid at all times and tending to bias thepiston structure to the open position.
 4. The combination of claim 1,wherein an indicator rod is affixed to the piston structure and isvisible externally of the circuit interrupter so as to be visible tomaintenance personnel.
 5. The combination of claim 1, wherein athree-way control valve controls the admission or exhausting ofhigh-pressure fluid on the opening face (8c) of the piston structure. 6.The combination of claim 1, wherein a liquefaction duct connects to theshock-absorbing chamber (51).
 7. In combination, a pneumatic operatingmechanism for a circuit interrupter including a cup-shaped steppedoperating piston having an enlarged piston head flange portion (8a) atone end movable within an enlarged high-pressure shock-absorbing chamber(51) at all times, said piston having low-pressure fluid constantlyacting on a portion (8b) of the closing face thereof, and means foralternating the high- and low-pressure fluid acting on the oppositeenlarged piston head flange portion (8c) to effect the opening andclosing operations of the circuit interrupter.
 8. The combinationaccording to claim 7, wherein the cup-shaped operating piston (8d) hasan enlarged guide portion at the other end thereof of smaller diameterthan the diameter of said enlarged piston head flange portion (8a), anda radially inwardly extending operating cylinder portion bearing againstthe smallest diameter of the piston.
 9. The combination according toclaim 1, wherein the head of the piston has a reduced protruding portionextending into a shock-absorbing chamber to cushion the closing strokeof the interrupter.
 10. The combination of claim 9, wherein a checkvalve is associated with the last-mentioned shock-absorbing chamber. 11.The combination according to claim 1, wherein a check valve isassociated with said shock-absorbing chamber.
 12. The combinationaccording to claim 3, wherein a check valve is associated with thesecond shock-absorbing chamber.
 13. The combination according to claim12, wherein a check valve is associated with the first-mentionedshock-absorbing chamber.